1. Field of the Invention
This invention relates to an information processing apparatus and a method therefor, and in particular to the scrambling of digital information data.
2. Description of the Related Art
Recently, with progress in digital signal information processing technology, a great amount of digital information such as moving pictures and still pictures can be recorded to small-sized magnetic media and can be transmitted to communications media by encoding the digital information with high efficiency.
As an application of such technology, an apparatus which enables only a specified user to decode a signal string by scrambling the string when encoding with high efficiency has been studied.
FIG. 1 shows a block diagram of a conventional information processing apparatus for scrambling a digital information signal.
As shown in FIG. 1, a block-forming unit 101 forms supplied digital information signal strings into blocks, corresponding to a finite number of signals. A rearranging unit 102 rearranges the block data strings which are sequentially supplied from the block-forming unit 101, in a predetermined order. A selector switch 103 selects either the block data string supplied from the block-forming unit 101 or the rearranged block data string supplied from the rearranging unit 102, and outputs the selected string. In other words, when the digital information signal needs to be scrambled, the block data string rearranged by the rearranging unit 102 is selected, while, when the signal does not need to be scrambled, the block data string from the block-forming unit 101 is selected.
In addition, the selector switch 103 also outputs a flag signal that represents which block data string has been selected.
FIG. 2 shows a block diagram of an information processing apparatus for decoding the scrambled digital information signal.
As shown in FIG. 2, a block-forming unit 201 forms a supplied signal string into blocks, corresponding to a finite number of signals. A rearranging unit 202 rearranges the block data strings which are sequentially supplied from the block-forming unit 201, in a predetermined order.
In accordance with the inputted flag signal, a selector switch 203 selects either the block data string supplied from the block-forming unit 201 or the rearranged block data string supplied from the rearranging unit 202, and outputs the selected string.
In other words, with respect to the scrambled information signal, the block data string rearranged by the rearranging unit 202 is selected, while, with respect to the information signal that has not been scrambled, the block data string from the block-forming unit 201 is selected.
The above-described conventional scrambling process requires the flag signal that represents whether or not scrambling has been performed, and it is essential that an apparatus and a recording medium, connected to the process, can respond to the flag signal. For example, the recording medium requires an extra recording region for recording the flag signal. As a result, disadvantageously, the recording medium has non-compatibility between the data format of the extra recording region and the data format of previous data. In addition, the conventional apparatus needs a large number of storage devices for data rearrangement for scrambling, which causes its circuit size to be large.
In view of the above-described background, it is an object of the present invention to provide an information processing apparatus and a method therefor which do not need an extra flag signal, and are capable of scrambling and decoding with a small-sized circuit.
To this end, according to an aspect of the present invention, the foregoing object has been achieved by the provision of an information processing apparatus or method including: input means (or a step) for inputting digital information data; block-forming means (or a step) for forming digital information data inputted to the input means (or step) into blocks, each corresponding to a plurality of samples; orthogonal transformation means (or a step) for orthogonally transforming the block data formed by the block-forming means (or step); and scrambling means (or a step) for transforming predetermined component data included in the orthogonal transformation data formed by the orthogonal transformation means (or step), to scramble the digital information data.
According to another aspect of the invention, the foregoing object has been achieved by the provision of an information processing apparatus for decoding data encoded by a process in which a digital information data is formed into blocks which each correspond to a plurality of samples, orthogonal transformation is performed with respect to the formed block data, a predetermined coefficient included in the orthogonal transformation data formed in the orthogonal transformation is transformed to scramble the digital information data, and the orthogonal transformation data including the transformed coefficient is encoded, the information processing apparatus (method) having: decoding means (or a step) for decoding the encoded data; block-forming means (or a step) for forming the decoded data into blocks which each correspond to a plurality of samples; inversion-scrambling means (or a step) for transforming a predetermined coefficient in the block data formed by the block-forming means (or step); and inversely-orthogonal-transformation means (or a step) for performing inversely-orthogonal-transformation of the block data outputted by the inversion-scrambling means (or step).
Other objects, features and advantages of the present invention will become apparent from the following detailed description and the attached drawings.